The concept and application of the hottest pipelin

Concept and application of pipeline (Part 1)

pipeline is a device connected by pipes, pipe connectors and valves for transporting gas, liquid or fluid with solid particles

generally, the fluid flows from the high-pressure part of the pipeline to the low-pressure part after being pressurized by blowers, compressors, pumps and boilers, and can also be transported by the pressure or gravity of the fluid itself. Pipelines are widely used. The main components are 17.5 feet (5.33 meters) long and 5.5 inches "sponge", which instantly produces a horizontal or vertical displacement ruler (1.68 meters) wide and 1.5 feet (0.46 meters) high in water supply and drainage n=100; Other scales, heating, gas supply, long-distance transmission of oil and natural gas, agricultural irrigation, hydraulic engineering and various industrial devices

when the fluid flow is known, the size of the pipe diameter depends on the allowable flow rate or the allowable friction resistance (pressure drop). When the flow rate is large, the pipe diameter is small, but the pressure drop increases. Therefore, when the flow rate is high, the pipeline infrastructure investment can be saved, but the operation energy consumption cost of power equipment such as pumps and compressors increases. In addition, if the flow rate is too large, it may bring some other adverse factors. Therefore, the pipe diameter should be determined according to the construction investment, operation cost and other technical factors

the connection methods between pipes, pipe connectors, valves and inlet and outlet nozzles on equipment are determined by the nature, pressure and temperature of the fluid, as well as the material, size and installation site of the pipe. There are mainly four methods: threaded connection, flange connection, socket connection and welding

threaded connection is mainly applicable to small-diameter pipes. When connecting, it is generally necessary to wrap fluoroplastic sealing tape around the threaded connection part, or apply thick paint, hemp wire and other sealing materials to prevent leakage. When the pressure is above 1.6 MPa, gaskets are usually added to the end face of the pipe for sealing. This connection method is simple and can be disassembled and reassembled, but the union must be installed at the appropriate place of the pipeline to facilitate disassembly and assembly

flange connection is applicable to a wide range of pipe diameters. During connection, different flanges and sealing gaskets are selected according to the nature, pressure and temperature of the fluid, and the gasket is clamped with bolts to maintain sealing. Flange connection is mostly used at the pipe sections that need to be disassembled and assembled frequently and at the places where pipes and equipment are connected

socket connection is mainly used for the connection between cast iron pipes, concrete pipes, clay pipes and their connectors. It is only applicable to water supply, drainage and gas pipelines working under low pressure and normal temperature. During connection, hemp thread, cotton thread or asbestos rope is usually filled in the groove of the socket, and then filled with asbestos cement or lead and other materials. Rubber sealing ring can also be filled in the socket to make it more flexible and allow a small amount of movement of the pipe

the welded connection has the best strength and tightness. It is suitable for all kinds of pipes, saving labor and materials, but the pipes and pipe connectors must be cut off during disassembly

the main pipelines for water supply, drainage, heat supply and gas supply in cities and long-distance oil and gas pipelines are mostly laid underground, while the process pipelines in factories are mostly laid on the ground for easy operation and maintenance. The passage, support, slope, drainage and exhaust, compensation, heat preservation and heating, corrosion prevention and cleaning, identification and painting and safety of pipelines are important issues for both above ground and underground laying

pipelines on the ground should try to avoid crossing with roads, railways and navigation channels. When the intersection cannot be avoided, the crossing height at the intersection should also enable pedestrians, vehicles and ships to pass safely. Underground pipelines are generally laid along roads, and appropriate distances are maintained between various pipelines for installation and maintenance; The surface of the heat supply pipeline has an insulating layer, which is laid in the trench or protective pipe. It should avoid being crushed by soil and make the pipe expand and move

the pipeline may bear many kinds of external forces, including its own weight, the thrust of fluid acting on the pipe end, wind and snow load, soil pressure, thermal stress caused by thermal expansion and contraction, vibration load, earthquake disaster, etc. In order to ensure the strength and rigidity of the pipeline, various supports (hangers) must be set, such as movable supports, fixed supports, guide supports and spring supports. The setting of the support is determined by the diameter, material, wall thickness and load of the pipe. The fixed support is used to control the thermal elongation of the pipeline in sections to make the expansion joint work evenly; The guide bracket makes the pipe move only axially